Microsoft does not have immediate plans to port the Windows Phone 7 mobile OS to tablets, a company official said on Monday.

Windows Phone 7 is designed for small-screen devices such as smartphones and is not designed to work with larger screen devices, said Greg Sullivan, senior product manager at Microsoft, at the Windows Phone 7 launch event in New York.

The company will instead continue to adapt its PC operating system, Windows 7, to tablets as it offers a rich application experience and touch-based capabilities, Sullivan said. Tablets require a more PC-like experience, and it makes sense to design a low-power version of Windows 7 to work on tablets, he said.

The strategy puts Microsoft at odds with some of its biggest competitors in the mobile phone market, which are already making inroads in the new tablet segment. Apple's iPad carries the same iOS architecture core that powers the iPhone.

A number of device makers, including Samsung, have announced tablets based on Android, which was designed for mobile phones. Research In Motion recently said it plans to introduce a tablet built on a new operating system that is expected to run its BlackBerry phones in the future.

Tablets are designed to combine e-reading, gaming, Web surfing and video capabilities on a single handheld device. Users of tablets like the iPad say that the mobile operating systems offer advantages over traditional computer OSes, like instant on and access to an existing application store.

However, Sullivan argues that there are advantages to using Windows 7 on tablets instead of the phone software. Windows 7 brings a stronger set of networking and printing capabilities than Windows Phone 7, which is a much slimmer OS, he said. The stronger software and driver stack in Windows 7 will also make it easier for tablets to talk to a larger range of hardware devices, he said.

Also, stretching an OS like Windows Phone 7 means that applications designed for smaller screens won't look good on the larger screens, Sullivan said.

Some tablet makers say they are implementing Windows 7 because of the capability to run a wider set of applications. Hewlett-Packard has said it will release a tablet with Windows 7, which is targeted at the enterprise. Dell has also shown off a convertible tablet with Windows 7.

Microsoft has also previewed Windows Compact Embedded 7, which has been shown on embedded systems like tablets and is scheduled for release to manufacturing this quarter.

Samsung talked to Microsoft about using Windows Phone 7 on tablets, but was told that such plans were not on Microsoft's road map, said Ray Vinson, senior manager of enterprise mobility, strategy and product planning at Samsung Telecommunications America.

Microsoft may have decided to focus on ensuring that the OS works properly on smartphones or may have found some limitations to doing so and decided against it, he said.

The Windows Phone 7 user interface is ideally suited for tablets, said Ross Rubin, executive director of industry analysis for consumer technology at NPD. The panorama view capability extends the screen beyond its normal confines, allowing users to horizontally slide through content either in portrait or landscape mode.

He suspects that Microsoft may look at new form factors with upcoming versions of Windows Phone 7, but that it probably decided to initially focus on getting the mobile phone launch right. "That is the largest device category in the world. It's very important Microsoft be strong there, so that was the first priority," Rubin said.